Uncertain nitrogen prices, supplies may affect application timing

Rising nitrogen prices, uncertain spring supplies, and unseasonably high temperatures may push farmers to apply nitrogen outside of their normal application windows, says University of Missouri Extension nutrient management specialist John Lory.

"We may be in unprecedented times with respect to nitrogen management decisions for the 2022 growing season," says Lory. "Nitrogen pressures for 2022 are pushing farmers away from best management practices for nitrogen management and driving more people to fall nitrogen applications."

Market reports show large disparities in nitrogen costs, with some fall prices much lower than projected prices for early 2022. Industry representatives predict that spring supplies might be tighter than normal. This raises concern that supplies may not be available to farmers who wait until spring, says Ray Massey, MU Extension professor of agricultural and applied economics.

These uncertainties may lead to more farmers applying fall nitrogen this year, says Lory.

Use best management practices

Timing of nitrogen fertilizer application is complex. There are substantial risks associated with applying too early or too late. The right time is a moving target that depends on weather and other factors.

Pressures on farmers to apply more nitrogen earlier in the fall, coupled with higher-than-normal soil temperatures, make it highly likely that nitrogen will convert to nitrate this fall. This leaves cornfields susceptible to leaching losses this winter and spring, says Lory.

"We are expecting nitrogen to be available eight months from now (next June and July) when the corn crop needs that nitrogen. Is that realistic?" he says.

Corn can lose nitrogen in two main ways: below the root zone and through the air. Losses can happen in the spring when nitrogen leaches out of the root zone as nitrate-nitrogen. Losses may also occur in late spring and early summer when warm soils become saturated.

To prevent the most loss and improve efficiency, apply nitrogen close to time of uptake, Lory says. Focus on in-season applications, which bypass the times of the season when losses are most likely.

With fall nitrogen applications, soil temperatures are critical

The gold standard for fall nitrogen management is to inject anhydrous ammonia into soil when the soil temperature is below 40°F. in the southern half of Missouri and below 50°F. in northern Missouri. The right soil conditions and temperatures are critical to preventing nitrogen losses and leaching, says Lory.

Unseasonably warm weather in the Midwest pushed back typical application dates in many areas. In mid-October, 6-inch soil temperatures in Boone County, in mid-Missouri, averaged 70°F., nearly 10°F. above long-term averages.

Lory recommends checking MU Extension Agricultural Weather Network for Missouri at agebb.missouri.edu/weather/reports/soysoil6.asp for soil temperatures at 6-inch depth.

Have a plan in place

Losses are not certain but do happen regularly. For example, many Missouri farmers had nitrogen deficits due to the wet, cool weather in spring 2021.

The best way to manage risk of nitrogen loss is to have a plan to sidedress nitrogen to the corn if there is evidence of significant loss. Lory's research shows that sidedressing through corn tasseling usually maximizes yield. Later applications still increase yield.

The best way to check for nitrogen deficiency is to compare corn color to control areas with plenty of nitrogen. Private companies can help document nitrogen need for in-season applications. Options for application include high-clearance applicators (available at some fertilizer dealers) and aerial applications.

Consider price, supplies, and application method

"Farmers will make their best decisions about managing risks around the price of fertilizer, availability of fertilizer, and how to get fertilizer applied in their system," says Lory. Early applications require tracking the potential for nitrogen loss through the winter and spring and having a plan to document losses and, if needed, apply rescue applications.

For more information on nitrogen management, go to extension.missouri.edu/programs/nutrient-management/nm-nitrogen.